Fuse holder

ABSTRACT

A fuse holder provides a safe device for connecting fuses to a three-phase busbar device. Each phase includes a corresponding load conductor and line conductor mounted within a housing. A mechanical lock is provided for each phase that locks a knife of the fuse to one of the conductors for the phase. In a further aspect, the fuse knives are frictionally locked within the housing. In both the mechanical lock and frictional lock, a release mechanism is provided that can be activated by a screwdriver to release the fuse knives from the fuse holder. In another aspect, certain conductors are provided with heat dissipation wings that contact the housing to dissipate heat generated by current flowing through the conductor.

PRIORITY CLAIM

This application is a utility filing from and claims priority to U.S.Provisional Application No. 63/116,340, filed on Nov. 20, 2020, theentire disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a fuse holder, and particularly to athree-pole finger-safe holder for Class CF fuses.

U.S. Pat. No. 10,700,464 (the '464 patent), the disclosure of which isincorporated herein by reference, discloses a device for a busbar systemthat includes electrical connection contacts which are configured aspassable through feed-through openings of a contact protection baseplate module of the busbar system. The electrical contacts areinsertable into uniformly spaced contact openings located below thefeed-through openings of busbar modules provided inside the base platemodule for producing a direct electrical and mechanical connection tothe busbar modules. Various electrical modules, such as a motor controlunit, display unit and fuse switch disconnector, can be mounted to thebusbar system.

The busbar device disclosed in the '464 patent provides for simplemounting and removing of various electrical devices to a busbar, whileproviding a high degree of contact protection. There is a need for afuse holder that provides similar benefits and protections.

SUMMARY OF THE DISCLOSURE

A fuse holder is disclosed herein that incorporates features to providea finger-safe device for connecting a three-pole fuse to a busbardevice. The fuse holder includes a housing containing electricalconductors for connecting the fuse knives to the busbar device and toload terminals. In one feature, the housing includes an engagementmechanism configured for releasably engaging the fuse holder, with fusesmounted therein, to a busbar device. In another feature, the fuse holderincludes a locking mechanism that locks the knife or knives of a fusewithin the fuse holder. In one embodiment, the locking mechanism is amechanical lock in which the knife and at least one conductor includes ahole that receives a spring-biased needle to prevent removal of thefuse. A release mechanism is provided that allows use of a screwdriverto displace the needle out of the holes in the knife and conductor.

In another feature of the disclosed fuse holder, certain conductors ofwithin the fuse holder include wings that are arranged to contact asurface of the fuse holder housing. The wings are configured to conductaway heat generated by current flowing through the conductor, inparticular conducting the heat to the housing where the heat can bedissipated by convection with the outside atmosphere. The housingmaterial has a high thermal conductivity to facilitate extraction anddissipation of heat from the fuse holder.

In another embodiment, the fuse holder includes a mechanism thatautomatically ejects the fuse from the fuse holder a sufficient distanceto break the electrical contact between the fuse knives and the copperconductors within the fuse holder. The mechanism includes aspring-biased carriage surrounding each pair of line and load conductorsin which the carriage is biased to apply a force against a fuse knifeintroduced into the carriage to provide frictional engagement at theelectrical contact between the fuse knife and the associated copperconductor. The carriage further includes a release post that allows theuser to release the force on the fuse knife using a tool that leveragesthe release post at a safe location on the fuse holder without risk oftouching the live conductors inside the fuse holder. In a furtherfeature of the fuse holder disclosed herein, an automatic ejectionelement pushes the fuse away from the fuse holder once the frictionalengagement between the fuse knife and conductor is released.

In a further aspect of the disclosure, the fuse holder is configured tohave an optimized form factor with a minimal profile so that the fuseholder does not occupy excessive space on the busbar device. Thisoptimized form factor is achieved, in part, by locating the three phaseconnections in a compact pattern, with two of the phase connectionsadjacent each other and the third phase connection above the other two.This arrangement of the three phase connections is achieved, in part, bythe configuration of the line and load conductors housed within the fuseholder.

In another aspect, the fuse holder includes a spring-biased latch platethat allows the fuse holder to be easily engaged to a busbar device. Thelatch plate can be engaged to the base plate of the fuse holder so thatit is out of the way of the coper conductors contained within theholder.

In yet another aspect of the disclosure, the fuse holder is designed forsimplified assembly. The carriages described above can be clipped intothe first front plate and the ejectors can be inserted into appropriateslots in the carriages. The line and load conductors are carried by anintermediate plate that can be readily engaged with a first front plateso that the fuse contacts of the line and load conductors are properlyoriented within the carriages. The first front plate, intermediate plateand latch plate can be sandwiched between a base plate and a cover, withthe base plate and cover configured to snap together.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a fuse holder according to the presentdisclosure.

FIG. 2 is an exploded view of the fuse holder shown in FIG. 1 .

FIG. 3 is a detailed view of a fuse carriage and ejection feature of thefuse holder shown in FIGS. 1-2 .

FIG. 4 is a perspective view of a housing for the fuse holder shown inFIGS. 1-2 .

FIG. 5 is a perspective view of a first front plate for the fuse holdershown in FIGS. 1-2 .

FIG. 6 is a perspective view of a carriage for the L₁ and L₃ conductorsfor the fuse holder shown in FIGS. 1-2 .

FIG. 7 is a perspective view of a carriage for the L₂ conductors for thefuse holder shown in FIGS. 1-2 .

FIG. 8 is a perspective view of a base plate for the fuse holder shownin FIGS. 1-2 .

FIG. 9 is a perspective view of an intermediate plate for the fuseholder shown in FIGS. 1-2 .

FIG. 10 is a perspective view of a latch plate for the fuse holder shownin FIGS. 1-2 .

FIG. 11 is a perspective view of ejectors for the fuse holder shown inFIGS. 1-2

FIG. 12 is a perspective view of the L₁ load conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 13 is a perspective view of the L₂ load conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 14 is a perspective view of the L₃ load conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 15 is a perspective view of the L₃ line conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 16 is a perspective view of the L₁ line conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 17 is a perspective view of the L₂ line conductor for the fuseholder shown in FIGS. 1-2 .

FIG. 18 is a side partial cross-sectional view of the fuse holder of thepresent disclosure showing a first step of receiving a fuse.

FIG. 19 is a side partial cross-sectional view of the fuse holder shownin FIG. 18 showing a second step of receiving a fuse.

FIG. 20 is a side partial cross-sectional view of the fuse holder of thepresent disclosure showing a first step of removing a fuse.

FIG. 21 is a side partial cross-sectional view of the fuse holder shownin FIG. 20 showing a second step of removing a fuse.

FIG. 22 is a perspective view of the fuse holder of the presentdisclosure mounted on a busbar device of the type shown in U.S. Pat. No.10,700,464.

FIG. 23 is perspective view of a fuse holder according to anotherembodiment of the present disclosure.

FIG. 24 is an exploded view of the fuse holder shown in FIG. 23 .

FIG. 25 is a detailed view of a fuse carriage and ejection feature ofthe fuse holder shown in FIGS. 23-24 .

FIG. 26 is a perspective view of a housing for the fuse holder shown inFIGS. 23-24 .

FIG. 27 is a perspective view of a first front plate for the fuse holdershown in FIGS. 23-24 .

FIG. 28 is a perspective view of a carriage for the L₁ and L₃ conductorsfor the fuse holder shown in FIGS. 23-24 .

FIG. 29 is a perspective view of a carriage for the L₂ conductor for thefuse holder shown in FIGS. 23-24 .

FIG. 30 is a perspective view of a biasing spring used with thecarriages shown in FIGS. 28-29 .

FIG. 31 is a perspective view of an intermediate plate for the fuseholder shown in FIGS. 23-24 .

FIG. 32 is a perspective view of a base plate for the fuse holder shownin FIGS. 23-24 .

FIG. 33 is a perspective view of a latch plate for the fuse holder shownin FIGS. 23-24 .

FIG. 34 is a perspective view of ejectors for the fuse holder shown inFIGS. 23-24 .

FIG. 35 is a perspective view of a spring used with the ejector of FIG.34 .

FIG. 36 is a perspective view of the L₂ line conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 37 is a perspective view of the L₁ line conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 38 is a perspective view of the L₃ line conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 39 is a perspective view of the L₁ load conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 40 is a perspective view of the L₂ load conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 41 is a perspective view of the L₃ load conductor for the fuseholder shown in FIGS. 23-24 .

FIG. 42A is a perspective view of a fuse being inserted into the fuseholder of FIGS. 23-24 .

FIG. 42B is a side partial cross-sectional view of the fuse holder ofthe present disclosure showing a first step of receiving a fuse.

FIG. 43 is a side partial cross-sectional view of the fuse holder shownin FIG. 42B showing a second step of receiving a fuse.

FIG. 44 is a side partial cross-sectional view of the fuse holder of thepresent disclosure showing a first step of removing a fuse.

FIG. 45 is a side partial cross-sectional view of the fuse holder shownin FIG. 44 showing a second step of removing a fuse.

FIGS. 46A-46B are perspective view of the fuse holder of the presentdisclosure mounted on a busbar device of the type shown in U.S. Pat. No.10,700,464.

FIG. 47 is a perspective view of a fuse holder of another embodiment ofthe present disclosure.

FIG. 48 is an exploded vide of the fuse holder shown in FIG. 47 .

FIG. 49 is a second exploded vide of the fuse holder shown in FIG. 47 .

FIG. 50 is a top view of the fuse holder shown in FIG. 47 with the coverremoved.

FIG. 51 is a side cut-away view of the fuse holder shown in FIG. 47 withtwo fuses engaged to the holder.

FIG. 52 is an enlarged view of the locking mechanism of the fuse holderof FIG. 51 for locking the knife blades of the fuse.

FIG. 53 is the side cut-away view of the fuse holder shown in FIG. 51with a tool used to release the locking mechanism.

FIG. 54 is an end perspective view of the fuse holder shown in FIG. 47 ,with an end wall of the base plate removed.

FIG. 55 is a perspective view of the fuse holder of FIG. 47 with thecover and the base plate removed and three fuses engaged to the fuseholder.

FIG. 56 is a perspective view of the fuse holder of FIG. 47 mounted on aconventional cross-board busbar device.

FIG. 57 is a top perspective view of the fuse holder of FIG. 47 mountedon a massive busbar device using an adapter.

FIG. 58 is a bottom perspective view of the fuse holder and adaptermounted on the massive busbar device of FIG. 57 .

FIG. 59 is a top perspective view of a modified fuse holder mounteddirectly on a massive busbar device.

FIG. 60 is a bottom perspective view of the fuse holder mounted on themassive busbar device shown in FIG. 59 .

FIG. 61 is a side view of the fuse holder mounted on the massive busbardevice shown in FIG. 59 .

FIG. 62 is a partial cross-section view of the fuse holder shown in FIG.61 .

FIG. 63 is a cut-away perspective view of the fuse holder shown in FIG.61 .

FIG. 64 includes perspective views of the conductors of the fuse holdershown in FIG. 61 .

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings and described in the following written specification. It isunderstood that no limitation to the scope of the disclosure is therebyintended. It is further understood that the present disclosure includesany alterations and modifications to the illustrated embodiments andincludes further applications of the principles disclosed herein aswould normally occur to one skilled in the art to which this disclosurepertains.

A fuse holder 10 according to the present disclosure is shown in FIGS.1-2 . The holder includes a housing 10 a formed by a cover 11 mounted toa base plate 23 in a conventional manner. In one embodiment, the covercan be removably mounted by a snap latch engagement 11 a betweenopenings in the cover and projections on the base plate. In theassembled ready-to-use configuration shown in FIG. 1 , the holder 10includes three ejectors 40 that are depressed when a fuse is mounted tothe holder, and a terminal cover 43 that encloses terminals forelectrical connection to the load copper conductors within the holder.

As shown in the exploded view of FIG. 2 , the cover and base plateencloses the components of the fuse holder with a plate arrangement thatsupports the load conductors 26-28 and the line conductors 30-32. Thefuse holder further includes carriages 13, 15 and 17 corresponding torespective L₁, L₂, L₃ copper conductors 26-28 and 30-32. As described inmore detail herein, the carriages are movably supported on a first frontplate 22 of the plate arrangement so that the carriages can shiftrelative to the connecting knife of a fuse engaged to the fuse holder.The load conductors 26-28 are supported on a second intermediate plate24 of the plate arrangement in electrical contact with load wireterminals 35 that are also supported on the intermediate support plate.Each wire terminal is configured in a known manner for electricalconnection to a wire of an external device. Line conductors 30-32 arealso supported on the intermediate plate. The front plate 22 andintermediate plate 24 are fixed relative to the base plate so that theline and load conductors are held in a fixed position within the fuseholder. The fuse holder 10 includes an engagement mechanism for engagingthe fuse holder, and thus an array of fuses, to a busbar device. In oneembodiment, the engagement mechanism includes a latch plate 37 disposedbetween the intermediate plate and the back plate that is configured toreleasably latch the fuse holder 10 to a busbar device, such as thebusbar device disclosed in the '464 patent.

The stack up of the components is shown in more detail in FIG. 3 . Thecarriages 13, 15, 17 are supported on the first front plate 22 withcontact ends of the load conductor, such as L₃ load conductor 27, andline conductors, such as L₃ line conductor 32, extending through thecarriages. The ejectors 40 are also supported by the first front plate22 inside the carriages. As indicated by the arrow A in the enlargementof FIG. 3 , the carriages can move up and down relative to the firstfront plate 22 and relative to the contact ends of the line and loadconductors. Each carriage includes a spring, such as spring 19 b to biasthe carriages upward (to the right in FIG. 3 ) toward the fixed line andload conductors.

Details of the cover 11 are shown in FIG. 4 . The cover defines fusebays 50 a, b, c to receive fuses for the L₁, L₂ and L₃ phases. The bayscan be in the form of recesses in the cover sized to receive the fuse,such as a Class CF fuse. Each bay defines a pair of slots 51 a, 51 bthrough which the two knives K of the fuse extend when the fuse ismounted to the fuse holder. An ejector slot 54 is disposed between thetwo slots 51 a, 51 b to receive a respective ejector 40. An ejector toolopening 55 is associated with each fuse bay. The opening 55 is sized toreceive the working end of a tool used to release the correspondingcarriage 13, 15, 17, as described herein. The cover 11 further defines awire terminal bay 53 beneath the fuse bays. The wire terminal bay 53 isenclosed by the terminal cover 43 which can be snap-fit within the wireterminal bay.

As shown in FIGS. 2 and 4 , the three phases are arranged to define acompact profile or form factor. Thus, in the illustrated embodiment, theline and load conductors for the first and third phases are adjacent atthe lower end of the cover 11, while the line and load conductors forthe second phase are centered above the other two phases. Thus, the L₁fuse bay 50 a is adjacent the L₃ fuse bay 50 c and the L₂ fuse bay 50 bis centered above the other two bays. This arrangement provides acompact profile which allows several fuse holders and other electricaldevices to be conveniently mounted on a common busbar device. Thus, asshown in FIG. 22 , the fuse holder 10 can be mounted on across-board-type busbar device B, which can be configured like thedevice of the '464 patent to include several locations for receivingelectrical devices. The slim profile of the fuse holder 10 minimizes thearea of the busbar device covered by the fuse holder and leaves themajority of the busbar device B available for other electrical devices.

Details of the first front plate 22 are shown in FIG. 5 . The firstfront plate includes a lower stop 57 that projects from the first platesurface 22 a. The lower stop limits the downward movement of the L₁ andL₃ carriages 13, 17, respectively. The lower stop includes a pair ofretainer flanges 58 projecting upward to retain the two carriages, asbest seen in FIG. 3 . A pair of upper carriage stops 59 include retainerflanges 60 that also help retain and guide each of the two carriages 13,17, again as best seen in FIG. 3 . A similar lower stop 62 and retainerflange 63, and a similar pair of upper stops 64 and retainer flanges 65,are provided for the L₂ carriage 15 at an upper portion of the firstfront plate 22. A biasing spring support 61 is disposed between thepairs of upper stops 59 for the two lower carriages, and a springsupport 66 is provided between the upper stops 64 for the L₂ carriage.The spring supports 61, 66 support the biasing springs 19 a-19 c andprovide a reaction base for the biasing force generated by the springson the respective carriages.

The first front plate 22 includes ejector guides 68 positioned betweenthe lower and upper stops of each fuse bay. The guides are aligned withcorresponding ejector slots 54 in the cover 11. The guides 68 are thussized to slidably receive the ejectors 40 therein. As shown in moredetail in FIG. 11 , the ejectors 40 include a generally flat body 119that fits within the generally rectangular shape of the guides. The endof the body 119 bears against a fuse to push the fuse outward—i.e., toeject the fuse from the fuse holder 10. The body includes a pair ofprongs 120 that are configured to engage openings in the fuse to holdonto the fuse when it is ejected. The prongs can be configured for aslight press-fit with the openings in the fuse. The body defines acenter post 121 on which is mounted the ejection spring 41. The end ofthe body 119 defines retention hooks 122 that bear against an interiorwall of the ejector guide 68 to hold the ejector 40 within the guideeven as the spring 40 pushes the ejector body 119 outward. The retentionhooks thus limit the outward extension of the ejector 40, which in aspecific embodiment can be 5 mm. The body 119 can define a bore 124 thatcan receive the hasp of a padlock when the ejector 40 is in its unloadedposition, as shown in FIG. 1 . The padlock can prevent installation of afuse into the fuse holder 10.

Returning to FIG. 5 , the first front plate 22 defines a series of slotsthrough which portions of the line and load conductors extend. Thus,load slots 70 a-70 c and line slots 71 a-71 c are provided with pairs ofload slots and line slots (such as slot 70 a and 71 a) arranged so thatthe load conductor and line conductor flank the ejector guide 68.Moreover, the line and load slots are specifically arranged to receive arespective knife of the fuse (see FIG. 20 ). As shown in FIG. 3 , the L₃load conductor 27 is above the L3 line conductor 32 and on oppositesides of the ejector guide 68.

Details of the carriages are shown in FIGS. 6-7 . The L₁, L₃ carriages13, 17 can be of identical construction. The carriages 13, 17 include agenerally rectangular body 73 with a biasing spring plate 74 spanningthe body near the top of the body. As shown in FIG. 3 , the biasingspring 19 c is disposed between the spring support 61 and the springplate 74 of the carriage. The spring support 61 is fixed within the fuseholder 10 so that the spring 19 c exerts and upward force on the springplate 74 to bias the carriage upward. The body 73 further includes alower clamping plate 75 with a leaf spring element 76 and an upperclamping plate 77 with a leaf spring element 78. The lower clampingplate 75 and leaf spring element 76 are positioned to be beneath theline conductor 32 for the L₃ phase. The upper clamping plate 77 and leafspring element 78 are similarly arranged for the load conductor 27 forthe L3 ₂ phase. The same plate and leaf spring arrangement is providedfor the line and load conductors for the L₁ phase. As shown in FIG. 7 ,the carriage 15 for the L₂ fuse bay has a similar construction with thebiasing spring plate 84, lower plate 85, leaf spring element 86, upperplate 87 and leaf spring element 88.

It can be appreciated that the respective biasing springs 19 a, 19 b, 19c bear against the three carriages 13, 15, 17 to push the carriageupward toward the line and load conductors extending through thecarriages. In the biased position, the leaf spring elements 76, 78, 86,88 can bear against the respective line and load conductors in theabsence of a fuse supported by the fuse holder. The construction of thecarriages 13, 15, 17 provides one feature of the fuse holder of thepresent disclosure, as illustrated in FIGS. 18-19 . As shown in FIG. 18, a fuse F is positioned with each fuse knife K aligned with acorresponding slot 51 a, 51 b in the cover 11. The ejector 40 projectsout from the cover toward the body of the fuse F. Each knife K isaligned with a corresponding load conductor 26 and line conductor 30,and more specifically to the intersection between the conductor and theleaf spring element 76, 78. As each knife is advanced between theconductor and the leaf spring element the carriage 13, 15, 17 is pusheddownward so that the lower clamping plate 75 of the carriage approachesor abuts the lower stop 57 of the first front plate 22, as shown in FIG.19 . This movement of the carriage compresses the spring 74, which meansthat the spring applies a force against the carriage that pushes thecarriage toward the newly inserted knives K. This force essentiallyclamps each knife K between the corresponding conductor 26, 30 and thelead spring element 76, 78 of the carriage. The conductor 27, 32 isbacked by the conductor slot 70 a, 70 b so that the entire spring forceis devoted to clamping the knives of the fuse with sufficient force tohold the fuse in position against being inadvertently dislodged.

In one specific embodiment, the springs 19 a, 19 b, 19 c are coilcompression springs with a spring rate of 12.3 Nmm (108 lb./in) togenerate a force of 50 N in the baseline position shown in FIG. 18 , anda clamping force of 150 N in the position shown in FIG. 19 . The forcein the baseline position is not enough to prevent manual insertion ofthe fuse knives K into the fuse holder, but is enough to provide atactile feel during insertion. The clamping force is sufficient toprevent manual removal of the fuse from the fuse holder and to maintaina solid electrical connection between the fuse knives K and theconductors 26, 30. It is contemplated that the springs 19 a, 19 b, 19 ccan be other forms of springs or resilient components capable of beingcompressed and exerting a force when compressed.

Returning to FIGS. 6, 7 , each of the carriages 13, 17 include a releasepost 80, while the carriage 16 includes a release post 90. The releaseposts project into ejector tool openings 55 in the cover 11 (FIG. 4 ).As shown in FIG. 19 , the opening 55 is configured to receive theworking end of a tool T, such as a flat head screwdriver. The tool canbe used as a lever to push the release post 90, and thereby the carriage13, 15, 17 downward. This movement shifts the two clamping plates 75, 77(85, 87) and associated leaf spring elements 76, 78 (86, 88) downwardaway from contact with the respective fuse knife K, as shown in FIG. 21. In this configuration there is no meaningful friction force acting onthe fuse knives K to prevent the fuse from being disengaged and removedfrom the fuse holder 10. In this configuration the fuse can be readilyremoved manually. The carriage, and particularly the release post 90,can be configured so that a 1.6 mm movement of the carriage by the toolT is enough to release the fuse knives. The tool openings 55 and releaseposts 80, 90 are arranged to be physically remote from the line and loadconductors so that a tool introduced through the openings 55 cannotcontact the electrical conductors.

In a further feature of the fuse holder of the present disclosure, theejector 40 automatically operates to push the fuse F away from the fuseholder. In particular, a spring 41 pushes the ejector body 119 outwardwhich pushes the fuse far enough outward to electrically disconnect thefuse knives K from the line and load conductors inside the fuse holder.The prongs 120 on the ejector body 119 hold the fuse F so that it doesnot simply fall from the fuse holder when ejected. In one specificembodiment the spring 41 is a coil compression spring having a springconstant of 0.96 Nmm (8.5 lb/in) to produce a spring force of 3 N in itsneutral position with no fuse present, and a spring force of ION in itscompressed position when a fuse is engaged in the fuse holder. It iscontemplated that the springs 41 can be another form of spring orresilient component capable of being compressed and exerting a forcewhen compressed. It can be appreciated that the spring is compressed bythe body of the fuse F when it is pushed into the fuse holder asdepicted in FIGS. 18-19 . The ION fully compressed force of the spring41 is easily overcome by manual force and is not sufficient to dislodgethe fuse against the friction forces holding the fuse knives K in thefuse holder as described above. The ejector 40 and spring 41 areconfigured to push the fuse F away from the fuse holder by about 3 mm,which is a sufficient distance to allow the fuse to be grasped andcompletely removed.

Details of the intermediate plate 24 are shown in FIG. 8 . Theintermediate plate is configured to carry the conductors and align themwith the appropriate slots 70 a-c, 71 a-c in the first front plate 22.The bottom of the first plate includes terminal supports 110 forsupporting the wire terminals 35 in alignment with the terminal bay 53in the cover 11. The intermediate plate 24 further defines loadconductor slots 112 a, 112 b and 112 c for the corresponding loadconductors 26-28. The intermediate plate also defines line conductorslots 114 a, 114 b and 114 c for receiving the corresponding lineconductors 30-32. As shown in FIGS. 2 and 18 , the conductors areinserted into the respective slots 112 a-c, 114 a-c from the back of theintermediate plate 24. The back of the intermediate plate 24 includes anarray of flanges 115 a, 115 b configured to align and engage theconductors to hold them in position on the intermediate plate. Theflanges 115 a are configured to support the load conductors 26-28 sothat they extend through the appropriate slots 112 a-112 c and so thatthey are in electrical contact with the wire terminals 35 retained bythe terminal supports 110.

As shown in FIGS. 12-17 the line and load conductors are configured tobe carried by the intermediate plate 24 with the contact surfacesaccessible through the carriages 13, 15, 17. The L₁ load conductor 26,shown in FIG. 12 , includes an anchor leg 26 a that is seated within theflanges in the back of the intermediate plate 24, a fuse contact portion26 b for establishing electrical contact with the fuse knife K as shownin FIG. 19 , and a terminal contact portion 26 c for establishingelectrical contact with one of the wire terminals 35. Likewise, the L₂load conductor 27, shown in FIG. 13 , includes an anchor leg 27 a thatis seated within the flanges in the back of the intermediate plate 24, afuse contact portion 27 b for establishing electrical contact with thefuse knife K, and a terminal contact portion 27 c for establishingelectrical contact with one of the wire terminals 35. It can beappreciated that the anchor leg 27 a of the L₂ load conductor 27 islonger than the anchor leg of the other two conductors so that the L₂connection is oriented above the other two conductors in order tominimize the form factor of the fuse holder 10. The L₃ load conductor 28shown in FIG. 14 includes an anchor leg 28 a, fuse contact portion 28 band terminal contact portion 28 c that is similar to the L₁ loadconductor 26, but offset to an opposite side of the fuse holder.

The L₁ line conductor 30, shown in FIG. 15 , includes an anchor leg 30 aconfigured to be engaged by the flanges on the back of the intermediateplate 24. The anchor leg 30 a terminates in a fuse contact portion 30 bthat is arranged to oppose the load conductor fuse contact portion 26 bwithin the L₁ carriage 13. The other two conductors 31, 32 includerespective anchor legs 31 a, 32 a and fuse contact portions 31 b, 32 bthat are configured so that the line conductor fuse contact portionsoppose the load conductor fuse contact portions 27 b, 28 b within thecorresponding carriages 15, 17. In contrast to the load conductors, theline conductors include contact portions 30 c, 31 c, 32 c configured toengage contact slots S of a busbar device, such as busbar device B inFIG. 22 , on which the fuse holder is mounted. Thus, the L₁ lineconductor 30 includes a pair of busbar contact portions 30 c thatproject rearwardly from the conductor—i.e., toward the base plate 23when the fuse holder is assembled. The pair of contact portions 30 c arearranged to extend into one of the feed-through contact slot S in thebusbar device B, shown in FIG. 22 , to make electrical contact withcontacts within the device. The other line conductors 31, 32 includesimilar pair of busbar contact portions 31 c, 32 c that also projectrearwardly. The busbar contact portions 30 c-32 c are arranged to passthrough corresponding slots 101-103 in the base plate 23 shown in FIG. 9. As shown in FIG. 9 , the busbar slots 101-103 are vertically alignedand uniformly separated on the base plate. It can thus be appreciatedthat the anchor legs 30 a-32 a of the conductors are configured so thatthe fuse contact portions 30 b-32 b can be properly positioned withinthe carriages while the busbar contact portions 30 c-32 c are optimallylocated for engagement to a busbar device. In particular, the busbarcontact portions 30 c, 31 c, 32 c are arranged vertically, with the L₁connection at the top, the L₃ connection at the bottom and the L₂connection in the middle, to coincide with the conventional L₁-L₃positioning of the slots S in the busbar device B.

In order to optimize the form factor and minimize the profile of thefuse holder, the line conductors 30-32. are configured as shown in FIGS.15-17 so that the fuse contact portions, 30 b, 32 b, of two of thephases, L₁ and L₃ in the illustrated embodiment, are laterally adjacenteach other while the contact portion, 31 b, of the remaining phase, L₂,is vertically above the other two phases when the conductors are mountedwithin the fuse holder. As shown in FIG. 15 , the anchor leg 30 a is notlinear as it extends from the contact portion 30 b to the contactportion 30 c. Instead, the anchor leg is configured so that the twocontact portions are laterally offset relative to each other relative toa vertical axis V through the leg 30 a. The anchor legs 30 b, 30 c ofthe other two line conductors 31, 32, are similarly configured so thatthe respective contact portions 31 b, 31 c and 32 b, 32 c are laterallyoffset relative to each other.

The base plate 23 also includes busbar latch slots 106 that receive thelatches 118 formed on the latch plate 37 shown in FIG. 10 . As shown inFIG. 10 , the latches 118 are in the form of downward facing hooks thatare configured to engage slots in the busbar device on which the fuseholder is mounted. The latches 118 are biased by two springs 38 that aresupported on associated spring mounts 116 of the latch plate 37 and thatreact against associated spring stops 107 on the base plate 23. When thefuse holder is mounted on a fuse device, such as the busbar device Bshown in FIG. 22 , the latches 118 extend through latch openings L inthe device. The latches are pushed upward as the latches are insertedinto the openings L until the latches are fully disposed within theopening, at which point the springs 38 push the latches 118 down toengage a lower edge of the latch slots L. The latch plate 37 includesopposite rails 37 a on which the latches 118 are formed. The base plate23 includes clips 109 that engage the rails to hold the latch plate 37to the base plate. It can be appreciated that the latch plate does notinterfere with the line conductors or bus contact portions when the buscontact portions extend through the slots 101-103.

One benefit of the fuse holder 10 disclosed herein is that thecarriages, first front plate, second intermediate plate, latch plate,base plate, cover and ejector body can all be formed of a plastic orresin material. In one specific embodiment, these components can beformed of a polyamide. The cover, base plate and intervening plates canbe configured to snap together without the need for fasteners and tools.The interior of the cover 11 can be provided with flanges to receive theplates 22, 24 in snap-fit or force-fit engagement.

Another fuse holder 1010 according to the present disclosure is shown inFIG. 23 that presents a more streamlined envelope and improvedaesthetics. Details of the fuse holder 1010 are shown in FIGS. 24-46 .The general construction of the fuse holder 1010 is substantiallysimilar to the construction of the fuse holder 10. Features identifiedwith the numerals 10 xx of the fuse holder 1010 are have the samedescriptor and are substantially similar in form and function as thefeatures identified with the numerals xx of the fuse holder 10. Thus,like the holder 10, the fuse holder 1010 includes a housing 1010 aformed by cover 1011 engaged to a base plate 1023 that houses the lineand load conductors and supports the ejectors 1040 for ejecting fusesengaged to the holder. The fuse holder 1010 includes fuse bays 1050 a,1050 b, 1050 c for fuses engaged to the L₁, L₂ and L₃ electrical lines,respectively. The cover can include indicia 1052 a, 1052 b, 1052 cidentifying the particular line phase. As seen in FIG. 23 , each bayincludes two indicia that are oriented upside down relative to eachother. This configuration accounts for the fuse holder being mountedupright, as shown in FIG. 23 , or upside down. It can be further notedthat the L₁ and L₃ bays, 1050 a, 1050 c, each include indicia 1052 a forL₁ and indicia 1052 c for L₃, upside down relative to each other. It canbe appreciated that in the upright orientation shown in FIG. 23 , thefirst phase is on the left side of the fuse holder 1010 within bay 1050a. When the fuse holder is inverted, the first phase is still on theleft side, which places it in the bay 1050 c.

As shown in the exploded view of FIG. 24 , the fuse holder 1010 furtherincludes L₁, L₂, L₃, carriages 1013, 1015, 1017 that correspond to thecarriages 13, 15, 17 of the holder 10. As shown in FIG. 25 , thecarriages are biased by corresponding springs 1019 a, 1019 b, 1019 c,that operate in the same manner as the carriages and springs of theholder 10 as explained above in connection with FIG. 3 . The springs1019 a-c can be coil compression springs having a spring rate of 38.3Nmm (218 lb/in)

The fuse holder 1010 provides a more streamlined and aestheticappearance than the fuse holder 10. Thus, as shown in FIG. 26 , thecover 1011 is less “boxy” than the cover 11 (FIG. 4 ). In onemodification from the prior embodiment, the cover includes a pair ofangled side walls 1056 on either side of the L₂ fuse bay 1050 b. Theangled walls 1056 reduce the footprint of the upper end of the fuseholder 1010 since the space on either side of the L₂ fuse bay is unused.As with the prior embodiment, the cover 1011 defines ejector slots 1054,and knife slots 1051 a, 1051 b in each bay to receive the respectiveknives K of the fuse F (FIGS. 42A, 42B). The cover also defines threetool openings 1055, which receive a tool T, like the openings 55, toeject a corresponding fuse from the holder. Two of the openingsassociated with the L₁ and L₃ bays are generally the same as thecorresponding openings of the fuse holder 10. However, the tool opening1055 for the L₂ bay of fuse holder 1010 extends outside one angled wall1056, albeit in the same relative position as the opening 55 in the fuseholder 10.

In the prior embodiment fuse holder 10, the cover 11 has a depthsufficient to encompass the base plate 23. In the fuse holder 1011, itis the base plate 1023 that has a depth sufficient to encompass thecover 1011, as shown in FIGS. 24, 26 and 32 . The cover and base platecan be configured for releasable mechanical engagement, or can be fixedtogether such as by glue or welding. In certain embodiments, thereleasable mechanical engagement can include engagement latches 1011 aformed on either side of the cover that are configured for snap-fit orpress-fit engagement with corresponding ramps 1011 b defined on theinside of side walls 1023 a of the base plate 1023. As with the coverand base plate of the holder 10, the cover and base plate of the holder1010 are configured to be pressed together with a snap-fit or press-fitengagement between the latches 1011 a and ramps 1011 b.

The fuse holder 1010 includes a plate arrangement with a first frontplate 1022 that performs the same function as the first front plate 22of the prior embodiment, but does so in a narrower space, as can be seenby comparing FIG. 27 to FIG. 5 . Like the first plate 22, the firstfront plate 1022 includes stops and retainer flanges for supporting thecarriages 1013, 1015, 1017 and the biasing springs 1019. The first frontplate 1022 also includes the ejector guides 1068 for guiding andsupporting the ejectors 1040. Unlike the first front plate 22, the firstfront plate 1022 includes side walls 1022 b and 1022 d, and center wall1022 c projecting from a back wall 1022 a. These walls add stiffness tothe first front plate and fuse holder and electrically isolate the L₁and L₃ phases from each other and from the cover and base plate.Otherwise, the components of the first front plate 1022 are the same andfunction the same as the like components of the first front plate 22. Itcan be appreciated that the location and orientation of the carriages1013, 1015, 1017 and the features supporting the load conductors 1026,1027, 1028 and line conductors 1030, 1031, 1032 are dictated by theconfigurations of the fuses F and of the busbar device B to which thefuse holder is connected.

The L₂ carriage 1015 is substantially similar to the carriage 15,including the placement and orientation of the release post 1090.However, the L₁ and L₃ carriages 1013, 1017 are modified from thecarriages 13, 17 in that the release post 1080 is centrally locatedrelative to the width of the carriage. In the carriages 13, 17 of theprior embodiment, the release posts 80 were offset to an outboardposition. In order to maintain the reduced profile, the release posts1080 have been shifted centrally, together with the associated toolopenings 1055 that provide access to the release posts. Like the priorembodiment, the carriages are biased by a biasing spring 1019 that isdisposed between the biasing spring plate 1074, 1084 of the carriage andthe respective biasing spring support 1061, 1062 of the first frontplate 1022.

However, unlike the prior embodiment, the carriages 1013, 1015, 1017 donot include the leaf springs 78, 88. In the fuse holder 10, the leafsprings applied biasing pressure to the load and line conductors. In thefuse holder 1010, the biasing effect is provided by the configuration ofthe conductors themselves. As shown in FIGS. 36-41 , each of the loadconductors 1026, 1027, 1028 is similar in configuration to the loadconductors 26, 27, 28, with each load conductor including a terminalcontact portion, 1026 c for instance, for establishing electricalcontact with one of the wire terminals 1035, and a fuse contact portion,1026 b for instance, for establishing electrical contact with the knifeof a fuse. Each of the line conductors 1030, 1031, 1032 is similar inconfiguration to the line conductors 30, 31, 32, with each lineconductor including a fuse contact portion, such as 1030 b, forelectrical contact with the knife of a fuse, and a busbar contactportion, such as 1030 c, for establishing electrical contact with abusbar device. The six conductors are arranged in the fuse holder 1010to establish electrical contact between the fuse knives K and the wireterminals 1035 as well as the contact slots S in the busbar device B.The line conductors 1030-1032 are configured like the line conductors30-32 so that the busbar contact portions are arranged vertically fromL₁ to L₃, while the fuse contact portions are arranged with the L₁ andL₃ fuse contact portions laterally adjacent and the L₂ contact portionvertically above the other two phases.

In the fuse holder 1010, the fuse contact portions 1026 b, 1027 b, 1028b, 1030 b, 1031 b, 1032 b are oriented at less than a 900 angle relativeto the respective anchor legs 1026 a, 1027 a, 1028 a, 1030 a, 1031 a,1032 a. In one specific embodiment, the fuse contact portions are at an88° angle relative to the anchor leg. The fuse contact portions areconfigured to flex when contacted by the fuse knife K. To facilitatethis flexing, the conductors define a slot 1026 d, 1027 d, 1028 d, 1030d, 1031 d, 1032 d in the bend between the anchor leg and the fusecontact portion. This slot reduces the stiffness of the bend so that thefuse contact portions can deflect as needed when the fuse knife isinserted into engagement with the contact portions. The fuse contactportion, such as the contact portions 1028 b and 1032 b in FIG. 25 ,bears directly against the respective clamping plates 1077, 1075. Theknives K of the fuse are interposed between the fuse contact portions1028 b, 1032 b and the clamping plates 1077, 1075, to push the carriageupward (to the right in FIG. 25 ) against the biasing springs 1019. Asthe springs are compressed, they exert increasing pressure on the knivesK to effectively clamp the knives against the fuse contact portions.

Moving back to FIG. 31 , the second intermediate support plate 1024 issimilar to the second intermediate plate 24, albeit narrower to fitwithin the narrower envelope of the fuse holder 1010. As with theintermediate plate 24, the intermediate plate 1024 carries theelectrical conductors 26-28, 30-32, holding them in a fixed orientationwithin the base plate 1023. As mentioned above, the base plate 1023 ofthe fuse holder 1010 differs from the base plate 23 of the holder 10.However, like the prior base plate, the base plate 1023 includes theslots 1102, 1103 through which the busbar contact portions of the lineand load conductors extend. The base plate 1023 includes side walls 1023a, a top wall 1023 b and a bottom wall 1023 c configured to receive theintermediate plate 1024 with the electrical conductors supportedthereon, the first front plate 1022 with the carriages 1013, 1015, 1017and associated biasing springs supported thereon, and the cover 1011. Asreflected in FIG. 23 , the walls of the cover align with the walls ofthe base plate when the two components are in snap-fit engagement.

The fuse holder 1010 includes an engagement mechanism configured toengage the fuse holder to a busbar device. In one embodiment, theengagement mechanism can include a latch plate 1037 and biasing springs1038 that are identical to the latch plate 37 and spring 38 of the priorholder. The latch plate 1037 provides the interface for engaging thefuse holder 1010 to latch openings L of the busbar device B, asdescribed above, and as shown in FIGS. 46A, 46B.

The manner of insertion and removal of a fuse F on the fuse holder 1010is shown in FIGS. 42 a -45. The manner of operation is identical to theoperation of the fuse holder 10 shown in FIGS. 18-21 and as describedabove. To reiterate, the biasing springs 1019 bias the carriages 1013,1015, 1017 toward the fuse contact portions of the respective line andload conductors. As the fuse F is introduced into the holder, the knivesK move between the fuse contact portions (such as contact portions 1026b, 1030 b shown in FIG. 43 ) and the carriages to move the carriages tothe right in the drawings, thereby compressing the biasing springs 1019.As the fuse is pushed further into the fuse holder, the body of the fusecontact portions the ejector 1040 and compresses the spring 1041, whichcan have the same properties as the spring 41 discussed above. Thespring force of the biasing springs is calibrated to provide sufficientfrictional force to hold the fuse knives in position and avoidaccidental dislodgement. As shown in FIGS. 44-45 , the fuse can beremoved by levering the tool T against the release post 1080 to push thecarriage further to the right to relieve the frictional contact betweenthe carriage and the fuse knife K. When the frictional pressure isremoved, the spring 1041 pushes the ejector 1040 outward, which in turnpushes the body of the fuse F away from the fuse holder 1010. Theejector 1040 is configured similar to the ejector 40, as seen bycomparing FIG. 34 to FIG. 11 . One modification is that the ejectorincludes notches 1124 formed adjacent the prongs 1120. This featureprovides some flexibility to the prongs as they contact the body of thefuse F. The prongs deflect slightly when the fuse is pushed into theholder, and this slight deflection generates a force to assist thespring 1041 in ejecting the fuse from the holder.

Another embodiment of a fuse holder 2010 is shown in FIGS. 47-60 thateliminates the ejectors 40, 1040 of the previous embodiments and thatreplaces the spring-based frictional engagement of the fuse knife with adirect mechanical locking mechanism. Like the fuse holders 10 and 1010,the fuse holder 2010 includes a cover 2011 and base plate 2023 thathouse and insulate the line and load coppers disposed therein and thatcan be releasably mechanically engaged to each other. The cover 2011defines three fuse bays 2050 a-c, with indicia 2052 a-c provided toidentify the particular line of the particular line phase that theassociated fuse is to be connected across. The front cover includes aremovable terminal cover 2043 that allows access to wire terminals 2035that are in electrical contact with the L₁-L₃ load conductors 2026-2028as in the prior embodiments. The fuse holder 2010 includes a platearrangement with a front plate 2022 that supports carriages 2013-2017,and an intermediate plate 2024 that supports the load conductors and theline conductors 2030-2032, all in substantially the same manner as thefront and intermediate plates of the prior fuse holders. The fuse holder2010 includes an engagement mechanism configured to engage the fuseholder, with fuses mounted therein, to a busbar device. In oneembodiment, the engagement mechanism can include a cross-board latch2037 and a biasing spring 2038 integrated into the base plate 2023 andoperable in the same manner as the fuse holders 10, 1010. Thecross-board latch includes latches 2037 a similar to the latches 118 and1118 that are adapted to engage corresponding slots in the busbar deviceB as described above. The fuse holder 2010 orients the three phases inthe same manner as the fuse holders 10, 1010 with two phases laterallyadjacent and the third phase vertically oriented relative to the othertwo phases. It can be appreciated that the fuse holder 2010 issubstantially similar to the fuse holders 10, 1010, except for themodification described below.

In one modification from the other fuse holders, the conductors are eachprovided with a pair of spring-biased contacts for engaging thecorresponding knives of a fuse mounted on the fuse holder 2010. Usingthe L₂ load conductor 2027 as an example, each conductor includes a leg2027 a that includes a wire terminal contact 2027 c at one end and isbent into a fuse contact portion at the opposite end, which portionincludes two contacts 2027 b facing each other. As is known in the art,one of the contacts 2027 b is an extension of the leg 2027 a, while theother contact 2027 b is affixed to the leg in a known manner. The twocontacts 2027 b are capable of deflecting apart to receive the knife ofa fuse therebetween. In one feature of the fuse holder 2010, a wirespring 2027 d encircles the two contacts 2027 b to bias the two legstoward each other. The wire spring 2027 d is stretched on theintroduction of a knife between the contacts so that the increasedspring force clamps the knife between the contacts. The wire spring 2027d has a spring force that is primarily calibrated to simply hold thecontacts 2027 b in solid electrical contact with the fuse knife. Thespring force does not require significant manual force by the user topush the fuse knife between the contacts 2027 b. In particular, thespring force is not strong enough to clamp the fuse knife, as in thefuse holders 10 and 1010 described above.

As shown in FIG. 49 in particular, each load conductor 2026-2028 andeach line conductor 2030-2032 includes the same spring-biased fusecontact portion. The free ends of the contacts, such as contacts 2028 band 2032 b shown in FIG. 51 , are angled away from each other to helpguide the knife K of the fuse F between the contacts.

The load conductors 2026-2028 are configured so that the terminalcontacts 2026 c-2028 c are in contact with the wire terminals 2035 whenthe conductors are supported on the front plate 2022, in a mannersimilar to the prior embodiments. Likewise, the line conductors2030-2032 are configured so that the busbar contacts 2030 c-2032 cextend through the base plate 2023 in the manner described above whenthe line conductors are supported by the intermediate plate 2024.

As indicated above, the fuse holder 2010 does not rely upon spring forceand friction to hold the fuse knife between the contacts 2026 b-2028 b.Thus, the locking mechanism includes modifications to the carriages fromthe other fuse holders in the fuse holder 2010. Each phase includes acorresponding carriage 2013, 2015, 2017 that is slidably supported bythe front plate 2022. The carriages are generally elongated tear-dropshaped, as best seen in FIG. 50 , with a central opening 2017 b. Theopening is sized and arranged to fit over an anchor plate 2025 extendingfrom the front plate (FIG. 49, 50 ). The carriages, such as carriage2017 in FIG. 50 , are elongated to receive a biasing spring 2019 that isdisposed between a corresponding anchor plate 2025 and a locking body2018 that is fixed within the carriage 2017. Thus, the spring 2019 isconfigured to push the locking body 2018 downward toward a correspondingline conductor 2030-2032, as shown in FIG. 50 . The carriage 2017, aswell as the other carriages, includes a cam element 2017 a at the end ofthe carriage opposite the locking body 2018.

Details of the locking mechanism, and particularly the carriages andtheir operation, are best seen in FIGS. 51-53 , which focus on thecarriage 2017 that operates on the line conductor 2032. It is, ofcourse, appreciated that the other carriages are configured and operatedin the same manner. The locking body 2018 includes a needle 2018 aprotruding toward the conductor 2032. The near-most contact 2032 b ofthe conductor defines a hole 2032 e through which the needle 2018 aextends in the locking position of the carriage, as shown in FIGS. 51-52, although a hole can be provided in the other contact as well. Theknife K of the fuse F also defines a hole O through which the needlealso extends. It can be appreciated that the needle 2018 a preventsremoval of the knife K by mechanical interference between the needle thehole O in the knife. Since the locking feature of the carriage is due tothis mechanical interference, the spring force needed for the spring2019 is much less than the clamping spring forces required for the fuseholders 10, 1010. In particular, the spring force only needs to hold theneedle 2018 a in position within the hole 2032 e in the conductorcontact 2032 b and within the hole O of the knife. In one specificembodiment, that force is 5 N.

As best seen in FIG. 52 , the needle 2018 a includes a beveled tip 2018b. The beveled tip 2018 b is engaged by the knife as the knife K isinserted between the contacts 2032 b, at which point the angled surfaceof the beveled tip acts as a cam surface to push the needle and thelocking body 2018 away from the conductor 2032 (to the right in FIG. 52). This action pushes the locking body 2018 against the spring 2019 tocompress the spring against the anchor plate 2025. In one specificembodiment, the spring is compressed to a force of 15 N to allow theknife K to pass in between the contacts 2032 b. Once the hole O is linedup with the hole 2032 e in the contact, the spring 2019 pushes theneedle 2018 a into the hole to lock the knife.

The knife K is mechanically locked within the fuse holder by thespring-biased needle 2018. The lock can be easily released by a tool,such as a screwdriver S extending through a tool opening 2055 a, 2055 b,2055 c (see FIG. 50 ), as shown in FIG. 53 . As described above, thecarriage 2017 includes a cam element 2017 a at the end of the carriageopposite the locking body 2018. In particular, the carriage isconfigured so that the cam element 2017 a is outboard of the anchorplate 2025 when the carriage is mounted on the front plate 2022, asshown in FIGS. 50-53 . As best seen in FIG. 53 , the cam element definesa curved surface 2017 b that is contacted by the tip of the tool S. Asthe screwdriver S is pushed into the carriage the tip bears against thecurved surface 2017 b to gradually push the cam element, and thus thecarriage 2017 and the locking needle 2018 a, away from the knife K. Thiscamming motion compresses the spring 2019 as the needle is moved awayfrom the knife until the needle 2018 a moves out of the hole O in theknife K and the hole 2032 e in the contact. As noted above, the springforce when the needle leaves the hole O is about 15 N, which is easilyovercome by manual manipulation of the screwdriver S.

In an alternative embodiment, the tool opening 2055 a, 2055 b, 2055 ccan be replaced with a manually operated button that includes theelongated tool S. Pressing the button pushes the tool against the curvedsurface 2017 b in the same manner as the use of a separate screwdriver.

As shown in FIG. 50 , the cam elements 2018 of the carriages 2017 foreach phase are aligned with each other. The cover 2011 defines threetool openings 2055 a, 2055 b, 2055 c aligned with the cam elements ofthe three carriages, as shown in FIG. 47 . Each opening includes anindicator arrow pointing to the particular phase associated with theparticular carriage so that the user can select which fuse to remove.

Another feature of the fuse holder 2010 is illustrated in FIGS. 49, 54and 55 . In this feature, each of the line conductors 2030-2032 areprovided with heat dissipation features. It is known that currentrunning through the conductors causes the temperature of the conductorsto increase. The conductors thus become heat generators within the fuseholder 2010. This feature directs the heat generated by the conductorsto the side walls 2023 a of the base plate 2023. In particular, at leasttwo of the conductors, 2030 and 2031, includes at least one wing, 2030 fand 2031 f, extending from a lateral edge of the corresponding leg 2030a, 2031 a, as best seen in FIG. 49 . As shown in FIG. 54 , the wings arearranged for direct heat transfer contact with the side walls 2023 a ofthe base plate 2023. The wings 2030 f, 2031 f are configured to extendalong most of the length of the corresponding legs to maximize the heattransfer surface for optimal heat dissipation. The wings can be integralwith the arm of the corresponding conductor or can be separatelyattached to the arm in a heat conductive manner. Preferably, the wingsare stamped with the arm of the conductor and then bent relative to thearm, as shown in FIG. 49 . The third conductor 2032 does not includesimilar wings because the conductor is centrally located within the fuseholder 2011.

In order to maximize the heat dissipation capability of the fuse holder2011, the base plate 2023 is formed of a heat conductive plastic orresin material. In one embodiment, the material has a thermalconductivity of at least 0.9 W/mK. In a specific embodiment, thematerial of the base plate is impregnated with heat conductivecomponents, such as glass fibers or conductive powders. One suitablematerial is polyamide 6.6 (PA66) that is a heat-stabilized, electricallyneutral moldable polyamide. Heat generated by the conductors 2030, 2031is thermally conducted by the wings 2030 f, 2031 f to the side walls2023 a, where convection draws the heat to the ambient air.

The fuse holder 2010 shown in FIG. 56 is mounted on a conventionalcross-board type busbar device B, in the same manner as the other fuseholders 10 and 1010. In particular, the latches 2037 a engage the busbardevice and the line conductor contacts are in electrical contact withslots in the device.

In FIGS. 57-58 , the fuse holder 2010 is shown mounted on a massivebusbar device B′ that includes large contact rails R for each of thephases. In some cases, the rails R can have a rectangular cross-sectionof 10 mm×30 mm. In this version, an adapter 2500 is provided on whichthe fuse holder is directly mounted. The adapter includes an interfacesimilar to the cross-board type busbar device B that is engaged by thelatches 2037 a to hold the fuse holder on the device with the contacts2030 c-2032 c of the line conductor in electrical contact with thecontact slots S, as described above. As shown in FIG. 58 , the adapter2500 includes a series of flanges 2510 that slidably engage the rails Rof the massive busbar device B′. A pair of latches 2511 at one end ofthe adapter are configured to releasably engage one rail R′ to lock theadapter, and thus the fuse holder 2010, to the busbar device B′. In oneembodiment, the latches 2511 are in the form of spring clips that aredepressed as the rail R′ is moved into engagement with the flange 2510and that can be depressed to release the adapter 2500 from the rails.

FIGS. 59-64 show a modified fuse holder 2010′ that is configured to bemounted directly to the rails R of the massive busbar device B′. In thisversion, the latch plate 2037 of the fuse holder 2010 is modified toprovide a series of flanges 2037 a′ that are configured to slidablyengage the rails R of the busbar device B′. The latch plate is furthermodified to include a pair of latches 2037 b′ at one end of the fuseholder that are configured to releasably engage one rail R′ to lock thefuse holder 2010′ to the busbar device B′.

As best shown in FIGS. 62-64 , the line conductors 2030′, 2031′ and2032′ are modified to include contacts specifically configured to engagethe rails R, R′. In particular, the busbar contact portions 2030 c′,2031 c′ and 2032 c′ are spring-type contacts that bear against the railsR, R′ when the fuse holder 2010′ is engaged to the rails by the flanges2037 a′. As shown in FIG. 64 , the line conductors 2030′-2032′ areidentical to the conductors 2030-2032 except for the modification of thebusbar contacts 2030 c′-2032 c′ described above.

The present disclosure should be considered as illustrative and notrestrictive in character. It is understood that only certain embodimentshave been presented and that all changes, modifications and furtherapplications that come within the spirit of the disclosure are desiredto be protected.

What is claimed is:
 1. A fuse holder for connecting a fuse, having apair of knives, to a busbar device, the fuse holder comprising: ahousing defining; a pair of fuse contact openings in a front face of thehousing configured to receive the knives of the fuse in a respective oneof the contact openings when the fuse is inserted into the fuse holder;and a busbar contact opening in a back face of the housing; a wireterminal mounted within said housing and accessible for electricalconnection with a wire of an external device; a line conductor mountedwithin said housing and including; a fuse contact portion aligned withone of the pair of fuse contact openings to contact a knife of the fusereceived through said fuse contact opening, and a busbar contact portionextending through said busbar contact opening and configured forelectrical connection to the busbar device when the fuse holder ismounted on the busbar device; a load conductor mounted within saidhousing and including; a fuse contact portion aligned with the other ofthe pair of fuse contact openings to contact a knife of the fusereceived through said fuse contact opening, and a terminal contactportion in contact with said wire terminal; and an engagement mechanismfor releasably engaging the fuse holder to the busbar device, wherein afuse can be engaged to the fuse holder prior to or after engagement ofthe fuse holder to the busbar device.
 2. The fuse holder of claim 1,further comprising a locking mechanism for releasably locking at leastone knife of the fuse to the fuse holder.
 3. The fuse holder of claim 2,in which at least one knife of the fuse includes an openingtherethrough, wherein one conductor of said line conductor and said loadconductor includes a hole therethrough that is aligned with the hole inthe at least one knife of the fuse when the knives are received in thecontact openings of the fuse holder; and the locking mechanism includesa locking member disposed within said housing and slidable relative tosaid one conductor, said locking member configured to simultaneouslyengage the hole in said one conductor and in the hole in the knife whenthe knives are received in the contact openings of the fuse holder, toprevent removal of the knife from the fuse holder.
 4. The fuse holder ofclaim 3, wherein the locking mechanism includes an elongated carriageslidably disposed within said housing, said carriage including; a needleforming said locking member and extending from one end of said carriagethat is aligned with said hole in said one conductor and sized to extendthrough said hole in said one conductor and said hole in said knife in alocking position; a spring disposed between said needle and said platearrangement configured to bias said needle to said locking position. 5.The fuse holder of claim 4, wherein said needle includes a beveled tipthat is arranged to be contacted by the knife as the knife is insertedinto the fuse holder to push the needle against the spring.
 6. The fuseholder of claim 4, wherein said carriage further comprises a cam elementdisposed at an opposite end of said carriage, said cam element defininga curved surface configured to move said carriage away from said lockingposition upon engagement with a tool against said curved surface.
 7. Thefuse holder of claim 6, wherein: said housing defines a tool openingaligned with said cam element of said carriage, said tool openingconfigured to receive an elongated tool for engagement with said curvedsurface.
 8. The fuse holder of claim 7, in which the fuse holder isconfigured for connecting three fuses to a three-phase electrical line,wherein: the fuse holder further comprises one of said pair of fusecontact openings, said busbar contact opening, said tool opening, saidwire terminal, said line conductor, and said load conductor for each ofthe three phases; the tool openings for the three phases are defined insaid housing aligned adjacent each other across a width of said housing;and the carriages for the three phases are supported within said housingwith the cam element of the carriages aligned adjacent each other withinthe housing and in alignment with a corresponding tool opening.
 9. Thefuse holder of claim 1, further comprising a plate arrangement mountedwithin said housing configured to support, in fixed relation to saidhousing, said load conductor and said line conductor so that said fusecontact portions of the load conductor and line conductor are eachaligned with a corresponding one of said pair of fuse contact openings,said plate arrangement further configured to support said line conductorso that said busbar contact portion extends through said busbar contactopening and to support said load conductor so that said terminal contactportion is in electrical contact with said wire terminal.
 10. The fuseholder of claim 1, in which the fuse holder is configured for connectingthree fuses to a three-phase electrical line, wherein: the fuse holderfurther comprises one of said pair of fuse contact openings, said busbarcontact opening, said wire terminal, said line conductor and said loadconductor for each of the three phases, wherein the line conductors foreach of the three phases are configured so that the busbar contactportions of the line conductors are vertically separated along a lengthof said housing for electrical engagement to the busbar device.
 11. Thefuse holder of claim 1, in which the fuse holder is configured forconnecting three fuses to a three-phase electrical line, in which thebusbar device includes a contact slot for each of the three phases, thefuse holder further comprising: one of said pair of fuse contactopenings, said busbar contact opening, said wire terminal, said lineconductor and said load conductor for each of the three phases; and aplate mounted within said housing and configured to; support said loadconductor and said line conductor for two of the three phases laterallyadjacent each other; and support said load conductor and said lineconductor for the third of the three phases vertically adjacent theother two phases along a length of the housing.
 12. The fuse holder ofclaim 1, wherein said housing defines a fuse bay including a recess in afront face of said housing configured to receive the fuse therein, saidpair of fuse contact openings arranged in said recess.
 13. The fuseholder of claim 12, in which the fuse holder is configured forconnecting three fuses to a three-phase electrical line, wherein: thefuse holder further comprises said fuse bay, one of said pair of fusecontact openings, said busbar contact opening, said wire terminal, saidline conductor and said load conductor for each of the three phases; andwherein said fuse bay for each of the three phases includes indiciaindicative of the corresponding one of the three phases.
 14. The fuseholder of claim 1, wherein the fuse contact portion of each of saidconductors includes; a pair of adjacent contacts; and a spring holdingsaid pair of contacts together, wherein said pair of contacts areconfigured to receive a knife of the fuse therebetween, and wherein oneof said pair of contacts adjacent said needle of said elongated carriagedefines said hole.
 15. The fuse holder of claim 1, wherein said housingincludes: a cover defining said front face; a base plate defining saidback face; and a releasable engagement between said cover and said baseplate to enclose said wire terminal, said line conductor and said loadconductor.
 16. The fuse holder of claim 1, in which the busbar deviceincludes a plurality of latch openings, wherein the engagement mechanismcomprises: a latch plate slidably disposed within said housing, saidlatch plate including at least two latches extending throughcorresponding latch slots in said back face of said housing andconfigured for engagement with the latch openings of the busbar device;and a latch biasing spring disposed between said latch plate and saidhousing to bias said latch plate to a locking position.
 17. A fuseholder of claim 2, further comprising: a plate arrangement mountedwithin said housing configured to support, in fixed relation to saidhousing, said load conductor and said line conductor so that said fusecontact portions of the load and line conductors are each aligned with acorresponding one of the pair of fuse contact openings, said platearrangement further configured to support said line conductor so thatsaid busbar contact portion extends through said busbar contact openingand to support said load conductor so that said terminal contact portionis in electrical contact with said wire terminal; wherein said lockingmechanism includes; a carriage slidably disposed within said housing andincluding a spring plate and pair of clamping plates, one each of theclamping plates facing the fuse contact portion of a corresponding oneof the line conductor and the load conductor; and a biasing springdisposed between said plate arrangement and said spring plate, saidbiasing spring configured to exert a spring force on said spring plateof said carriage to bias said clamping plates toward the fuse contactportions of the corresponding line and load conductor; wherein the fusecontact openings are arranged so that, when the fuse is inserted intothe fuse holder, each of the pair of knives of the fuse is insertedbetween and in frictional engagement with the fuse contact portion, of acorresponding one of the line conductor and the load conductor, and acorresponding one of said clamping plates, to thereby move the carriageagainst the spring force exerted on the carriage.
 18. The fuse holder ofclaim 17, further comprising: a tool opening defined in said housing;and a release post on said carriage, said release post accessible by anelongated tool extending through said tool opening, said release postconfigured to move said carriage against the spring force exerted on thecarriage to move said pair of clamping plates away from the fuse contactportions.
 19. The fuse holder of claim 18 wherein said release post andsaid tool opening are physically remote from the line and loadconductors so that a tool extending through said tool opening to accesssaid release post cannot contact the line and load conductors.
 20. Thefuse holder of claim 17, further comprising: an ejector opening definedin said housing; an ejector slidably mounted in the ejector opening tocontact the fuse when the fuse is inserted into the fuse holder; and anejector spring mounted within the housing to push the ejector throughthe ejector opening and against the fuse.
 21. The fuse holder of claim20, wherein said ejector opening is arranged between said pair of fusecontact openings defined in said housing.
 22. The fuse holder of claim17, wherein biasing spring is configured to generate a clamping force of50-150 N to clamp each of the pair of knives between the correspondingfuse contact portion and the corresponding clamping plate.
 23. The fuseholder of claim 17, in which the fuse holder is configured forconnecting three fuses to a three-phase electrical line, in which thebusbar device includes a contact slot for each of the three phases,wherein: the fuse holder further comprises one of said pair of fusecontact openings, said busbar contact opening, said tool opening, saidwire terminal, said line conductor, said load conductor, said carriage,said biasing spring and said release post for each of the three phases;said plate arrangement is configured to support said load conductor,said line conductor and said carriage for each of the three phases. 24.The fuse holder of claim 23, further comprising, for each of the threephases, an ejector slidably mounted in an ejector opening defined insaid housing for each of the three phases, said ejector configured tocontact a corresponding one of the fuses inserted into the fuse holder,and an ejector spring mounted within the housing to push the ejectorthrough the ejector opening and against the corresponding one of thefuses.
 25. The fuse holder of claim 24, further comprising: an ejectoropening for each of the three phases defined in said housing; an ejectorslidably for each of the three phases mounted in each ejector opening tocontact the fuse when the fuse is inserted into the fuse holder; and anejector spring for each of the three phases mounted within the housingto push a corresponding ejector through the corresponding ejectoropening and against the fuse, wherein the ejector opening for each ofthe three phases is arranged between said pair of fuse contact openingsfor each of the three phases.
 26. A fuse holder for connecting a fuse,having a pair of knives, to a busbar device, at one knife including ahole therethrough, and the busbar device having a contact slot, the fuseholder comprising: a housing defining; a plurality of walls defining anenclosure; a pair of fuse contact openings in a front wall of thehousing configured to receive the knives of the fuse in a respective oneof the contact openings when the fuse is inserted into the fuse holder;and a busbar contact opening in a back wall of the housing; a wireterminal mounted within said housing and accessible for electricalconnection with a wire of an external device; a line conductor having afuse contact portion and a busbar contact portion, said busbar contactportion configured to extend through the contact slot of the busbardevice when the fuse holder is mounted on the busbar device; a loadconductor having a fuse contact portion and a terminal contact portion;a plate arrangement mounted within said housing configured to support,in fixed relation to said housing, said load conductor and said lineconductor so that said fuse contact portions of the load and lineconductors are each aligned with a corresponding one of the pair of fusecontact openings, said plate arrangement further configured to supportsaid line conductor so that said busbar contact portion extends throughsaid busbar contact opening and to support said load conductor so thatsaid terminal contact portion is in electrical contact with said wireterminal; wherein at least one conductor of said line conductorsincludes at least one heat conductive wing, said plate arrangementconfigured to support the at least one conductor with said at least oneheat conductive wing in heat transfer contact with at least one wall ofsaid housing.
 27. The fuse holder of claim 26, wherein said at least onewall of said housing is formed of a material having a thermalconductivity of at least 0.9 W/mK.
 28. The fuse holder of claim 27,wherein the material is a plastic or resin impregnated with heatconductive components.
 29. The fuse holder of claim 28, wherein theplastic or resin is polyamide 6.6 (PA66).